A liquid crystal display is provided with a liquid crystal cell and a polarizing plate. The polarizing plate includes a protective film and a polarizer, and can be obtained by dyeing a polyvinyl alcohol film forming the polarizer with iodine, stretching the film and then laminating both sides of the resulting film with protective films. In a transmission liquid crystal display, this polarizing plate is mounted on either side of the liquid crystal cell and one or more of an optical compensation film may further be placed. In a reflection liquid crystal display, a reflector, a liquid crystal cell, one or more of an optical compensation film and a polarizing plate are arranged in the order of mention. The liquid crystal cell is made up of liquid crystalline molecules, two substrates for sealing in these molecules, and electrode layers for applying a voltage to the liquid crystalline molecules. The liquid crystal cell performs an ON/OFF display by differences in aligned states of liquid crystalline molecules, and there have been proposals for its display modes applicable to both transmission and reflection display devices, such as TN (Twisted Nematic), IPS (In-Plane Switching), OCB (Optically Compensatory Bend), VA (Vertically Aligned) and ECB (Electrically Controlled Birefringence) modes.
Optical compensation films are used in various liquid crystal displays for the purposes of getting rid of image coloration and enlarging a viewing angle. Hitherto used optical compensation films are birefringent drawn polymer films. In substitution for optical compensation films made of birefringent drawn films, it has also been proposed to use optical compensating films having on their respective transparent substrates optically compensating layers made from low-molecular or high-molecular liquid crystalline molecules. Since the liquid crystalline molecules are various in their alignment forms, the use thereof makes it possible to achieve optical properties unobtainable by use of traditional birefringent drawn polymer films. Further, there have been proposals of protective films designed to serve also as optical compensation films through addition of birefringence to the protective films constituting polarizing plates.
Optical properties of an optical compensation film are determined with reference to optical properties of a liquid crystal cell, specifically distinctions among the display modes as mentioned above. When liquid crystalline molecules are used, it becomes possible to make optical compensation films having diverse optical properties responding to various display modes of liquid crystal cells. As to optical compensation films using liquid crystalline molecules, those appropriate to various display modes have already been proposed.
For instance, at the black display time in a voltage-unapplied condition, optical compensation films for parallel-orientation liquid crystal cells double as optical compensators for liquid crystalline molecules oriented parallel to the substrate surface and improvers of viewing angle characteristics of polarizer's orthogonal transmittance (See Japanese Patent No. 3342417).
However, it is extremely difficult to perfectly provide optical compensation for a liquid crystal cell with no problems even when optical compensation films are used. For instance, it is not enough to compensate a liquid crystal cell alone, but it is necessary to compensate also a light leak in a direction of 45 degrees from the transmission axis of a polarizing plate. In addition, the use of two or more retardation films causes considerable drop in productivity because additional processes including a stacking process are added.